1. Field of the Invention and Related Art Statement
This invention relates to an endoscope apparatus containing an image guide or light guide as twisted on the tip side to have the visual field direction and curvature axis coincide or intersect at right angles with each other.
Recently, there are used many (medical) endoscopes whereby an elongate insertable part is inserted into a body cavity so that organs within the body cavity may be observed and diagnosed without incising the body. Also, in the same manner, there are used (industrial) endoscopes whereby an elongate insertable part is inserted into an engine or a device of a plant or the like so that the interior of the engine or device may be observed or inspected.
A visual field direction changing adapter which changes the visual field direction of an objective lens in the tip forming part at the front end of an endoscope, for example, to a side viewing direction from a straight viewing direction can be removably fitted to such endoscope.
A prior art example of an endoscope apparatus provided with the above mentioned visual field direction changing adapter is suggested in a Japanese utility model application No. 106348/1987 and is shown in FIGS. 1 and 2.
Of the internal structure which is not shown in this prior art example but is considered to be such and is therefore mentioned as a related art example, the cross-section on A--A in FIG. 1 is shown in FIG. 3, the cross-section on B--B is shown in FIG. 4 and the view as seen in the direction of the arrow C is shown in FIG. 5. In these drawings, a tip forming part 3 is provided at the tip of an insertable part 1 through a curvable tube part 2 and is fitted with a visual field direction changing adapter 7. The above mentioned curvable tube 2 is made curvable in the four directions of U, D, R and L by a U/D (UP/DOWN) rotary axis shown in FIG. 3 and an R/L (RIGHT/LEFT) rotary axis intersecting at right angles with it. By the way, the curving operation is made by pulling one and relaxing the other of respective pairs of curving operation wires 6.
Within the above mentioned curvable tube part 2, an image guide fiber bundle 4 and light guide fiber bundle 5 are arranged on a straight line inclined by 45 degrees, for example, to the R/L rotary axis respectively in the spaces held by the adjacent curving operation wires 6. The image guide fiber bundle 4 and light guide fiber bundle 5 are fixed to the above mentioned tip forming part 3 substantially equally to this arrangement (See FIG. 4) and these fixing positions are in such position relation that the light guide fiber bundle 5 may be located on the X axis shown in FIG. 5 and passing through the center of the image guide fiber bundle 4 and the center of the tip forming part 3.
The above mentioned visual field direction changing adapter 7 is formed of an illuminating window 8 consisting of a prism and cover lens for changing the light path from the straight viewing to the side viewing of an illuminating optical system and an observing window 9 consisting of a prism and cover lens the same as in an observing optical system so that the visual field direction may be the same direction as of the above mentioned X axis (See FIG. 5).
As the image guide fiber bundle 4 and light guide fiber bundle 6 are housed as displaced from the U/D rotary axis or R/L rotary axis, there are merits that the structure shown in FIG. 3 can be made more compact than in the case that they are housed on these axes and therefore the outside diameter of the curvable tube part 2 can be made smaller.
However, in case the visual direction changing adapter 7 is fitted as in FIG. 1, the visual field direction will not coincide with the U/D rotary axis direction.
In this related art example, the direction at 45 degrees with the U/D rotary axis direction is a visual field direction.
Therefore, when the curving operation is made, for example, in the U/D direction, in FIG. 3, the tip forming part 7 will rotatably move within a plane in which the center axis O includes that axis O and U/D rotary axis. In this case, as the visual field direction V is not included in the above mentioned plane, it will be difficult for the operator to anticipate where the visual field direction will be directed by the curving operation.
Therefore, such operation as, for example, of moving the part displaced from the center of the visual field to the center of the visual field will be difficult.
Also, in the case of changing the observing direction, the operation of setting it in a desired direction will be difficult. Such defects will be produced. The same problems will be produced also in the case of curving in the R/L direction.
2. Objects and Summary of the Invention
An object of the present invention is to provide an endoscope whereby the change of the visual field direction by the curving operation can be easily anticipated without making the curvable tube part thick.
Another object of the present invention is to provide an endoscope whereby the visual field direction can be changed or the like by fitting an adapter simple in the structure.
In the present invention, the tip side end parts of a light guide inserted through an insertable part and transmitting an illuminating light and of an image guide transmitting an optical image are secured so as to be parallel/vertical to the line connecting at least one pair of pivoting parts of a curvable tube part, are changed rotatably around the center- axis within the curvable tube part adjacent to this tip part and are inserted through positions away from the pivoting parts. Thus, both guides can be inserted through the curvable tube part without making it thick, in the case of fitting the tip adapter, the visual field direction and curvature axis direction can be made parallel/vertical and, in the case of the curving operation, the moving direction of the visual field can be easily anticipated. By using two image guides, a stereo-observation can be made. Further, in case a CCD is used instead of using the image guide, by twisting the signal line, the same effect will be obtained.